[2/5] iio: pulse: add TI ECAP driver

diff --git a/drivers/iio/pulse/Kconfig b/drivers/iio/pulse/Kconfig
new file mode 100644
index 0000000..9864d4b
--- /dev/null
+++ b/drivers/iio/pulse/Kconfig
@@ -0,0 +1,20 @@ 
+#
+# Pulse Capture Devices
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "Pulse Capture Devices"
+
+config IIO_TIECAP
+	tristate "TI ECAP Pulse Capture"
+	depends on SOC_AM33XX
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	 If you say yes here you get support for the TI ECAP peripheral
+	 in pulse capture mode.
+
+	 This driver can also be built as a module.  If so, the module
+	 will be called tiecap
+
+endmenu
diff --git a/drivers/iio/pulse/Makefile b/drivers/iio/pulse/Makefile
new file mode 100644
index 0000000..94d4b00
--- /dev/null
+++ b/drivers/iio/pulse/Makefile
@@ -0,0 +1,6 @@ 
+#
+# Makefile for IIO PWM Capture Devices
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_IIO_TIECAP)	+= tiecap.o
diff --git a/drivers/iio/pulse/tiecap.c b/drivers/iio/pulse/tiecap.c
new file mode 100644
index 0000000..8e2b3a0
--- /dev/null
+++ b/drivers/iio/pulse/tiecap.c
@@ -0,0 +1,493 @@ 
+/*
+ * ECAP IIO pulse capture driver
+ *
+ * Copyright (C) 2014 Linaro Limited
+ * Author: Matt Porter <mporter@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+#include "../../pwm/pwm-tipwmss.h"
+
+/* ECAP regs and bits */
+#define CAP1			0x08
+#define CAP2			0x0c
+#define ECCTL1			0x28
+#define ECCTL1_RUN_FREE		BIT(15)
+#define ECCTL1_CAPLDEN		BIT(8)
+#define ECCTL1_CAP2POL		BIT(2)
+#define ECCTL1_CTRRST1		BIT(1)
+#define ECCTL1_CAP1POL		BIT(0)
+#define ECCTL2			0x2a
+#define ECCTL2_SYNCO_SEL_DIS	BIT(7)
+#define ECCTL2_TSCTR_FREERUN	BIT(4)
+#define ECCTL2_REARM		BIT(3)
+#define ECCTL2_STOP_WRAP_2	BIT(1)
+#define ECEINT			0x2c
+#define ECFLG			0x2e
+#define ECCLR			0x30
+#define ECINT_CTRCMP		BIT(7)
+#define ECINT_CTRPRD		BIT(6)
+#define ECINT_CTROVF		BIT(5)
+#define ECINT_CEVT4		BIT(4)
+#define ECINT_CEVT3		BIT(3)
+#define ECINT_CEVT2		BIT(2)
+#define ECINT_CEVT1		BIT(1)
+#define ECINT_ALL		(ECINT_CTRCMP |	\
+				ECINT_CTRPRD |	\
+				ECINT_CTROVF |	\
+				ECINT_CEVT4 |	\
+				ECINT_CEVT3 |	\
+				ECINT_CEVT2 |	\
+				ECINT_CEVT1)
+
+/* ECAP driver flags */
+#define ECAP_POLARITY_HIGH	BIT(1)
+#define ECAP_ENABLED		BIT(0)
+
+struct ecap_context {
+	u32	cap1;
+	u32	cap2;
+	u16	ecctl1;
+	u16	ecctl2;
+	u16	eceint;
+};
+
+struct ecap_state {
+	unsigned long		flags;
+	unsigned int		clk_rate;
+	void __iomem		*regs;
+	u32			*buf;
+	struct ecap_context	ctx;
+};
+
+#define dev_to_ecap_state(d)	iio_priv(dev_to_iio_dev(d))
+
+static const struct iio_chan_spec ecap_channels[] = {
+	{
+		.type		= IIO_PULSE,
+		.channel	= 0,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index	= 0,
+		.scan_type = {
+			.sign		= 'u',
+			.realbits	= 32,
+			.storagebits	= 32,
+			.endianness	= IIO_LE,
+		},
+		.modified = 0,
+	},
+	IIO_CHAN_SOFT_TIMESTAMP(1)
+};
+
+static ssize_t ecap_attr_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct ecap_state *state = dev_to_ecap_state(dev);
+
+	return sprintf(buf, "%d\n",
+		       test_bit(ECAP_POLARITY_HIGH, &state->flags));
+}
+
+static ssize_t ecap_attr_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf,
+			       size_t len)
+{
+	int ret;
+	bool val;
+	struct ecap_state *state = dev_to_ecap_state(dev);
+
+	if (test_bit(ECAP_ENABLED, &state->flags))
+		return -EINVAL;
+
+	ret = strtobool(buf, &val);
+	if (ret)
+		return ret;
+
+	if (val)
+		set_bit(ECAP_POLARITY_HIGH, &state->flags);
+	else
+		clear_bit(ECAP_POLARITY_HIGH, &state->flags);
+
+	return len;
+}
+
+static IIO_DEVICE_ATTR(in_pulse_polarity, S_IRUGO | S_IWUSR,
+	ecap_attr_show, ecap_attr_store, 0);
+
+static struct attribute *ecap_attributes[] = {
+	&iio_dev_attr_in_pulse_polarity.dev_attr.attr,
+	NULL,
+};
+
+static struct attribute_group ecap_attribute_group = {
+	.attrs = ecap_attributes,
+};
+
+static int ecap_read_raw(struct iio_dev *idev,
+			struct iio_chan_spec const *ch, int *val,
+			int *val2, long mask)
+{
+	struct ecap_state *state = iio_priv(idev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Always return 0 as a pulse width sample
+		 * is only valid in a triggered condition
+		 */
+		*val = 0;
+		*val2 = 0;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = NSEC_PER_SEC / state->clk_rate;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info ecap_info = {
+	.driver_module = THIS_MODULE,
+	.attrs = &ecap_attribute_group,
+	.read_raw = &ecap_read_raw,
+};
+
+static irqreturn_t ecap_trigger_handler(int irq, void *private)
+{
+	struct iio_poll_func *pf = private;
+	struct iio_dev *idev = pf->indio_dev;
+	struct ecap_state *state = iio_priv(idev);
+
+	/* Read pulse counter value */
+	*state->buf = readl(state->regs + CAP2);
+
+	iio_push_to_buffers_with_timestamp(idev, state->buf, iio_get_time_ns());
+
+	iio_trigger_notify_done(idev->trig);
+
+	return IRQ_HANDLED;
+};
+
+
+static const struct iio_trigger_ops iio_interrupt_trigger_ops = {
+	.owner = THIS_MODULE,
+};
+
+static irqreturn_t ecap_interrupt_handler(int irq, void *private)
+{
+	struct iio_dev *idev = private;
+	struct ecap_state *state = iio_priv(idev);
+	u16 ints;
+
+	iio_trigger_poll(idev->trig, 0);
+
+	/* Clear CAP2 interrupt */
+	ints = readw(state->regs + ECFLG);
+	if (ints & ECINT_CEVT2)
+		writew(ECINT_CEVT2, state->regs + ECCLR);
+	else
+		dev_warn(&idev->dev, "unhandled interrupt flagged: %04x\n",
+			 ints);
+
+	return IRQ_HANDLED;
+}
+
+static int ecap_buffer_predisable(struct iio_dev *idev)
+{
+	struct ecap_state *state = iio_priv(idev);
+	int ret = 0;
+	u16 ecctl2;
+
+	/* Stop capture */
+	clear_bit(ECAP_ENABLED, &state->flags);
+	ecctl2 = readw(state->regs + ECCTL2) & ~ECCTL2_TSCTR_FREERUN;
+	writew(ecctl2, state->regs + ECCTL2);
+
+	/* Disable and clear all interrupts */
+	writew(0, state->regs + ECEINT);
+	writew(ECINT_ALL, state->regs + ECCLR);
+
+	ret = iio_triggered_buffer_predisable(idev);
+
+	pm_runtime_put_sync(idev->dev.parent);
+
+	return ret;
+}
+
+static int ecap_buffer_postenable(struct iio_dev *idev)
+{
+	struct ecap_state *state = iio_priv(idev);
+	int ret = 0;
+	u16 ecctl1, ecctl2;
+
+	pm_runtime_get_sync(idev->dev.parent);
+
+	/* Configure pulse polarity */
+	ecctl1 = readw(state->regs + ECCTL1);
+	if (test_bit(ECAP_POLARITY_HIGH, &state->flags)) {
+		/* CAP1 rising, CAP2 falling */
+		ecctl1 |= ECCTL1_CAP2POL;
+		ecctl1 &= ~ECCTL1_CAP1POL;
+	} else {
+		/* CAP1 falling, CAP2 rising */
+		ecctl1 &= ~ECCTL1_CAP2POL;
+		ecctl1 |= ECCTL1_CAP1POL;
+	}
+	writew(ecctl1, state->regs + ECCTL1);
+
+	/* Enable CAP2 interrupt */
+	writew(ECINT_CEVT2, state->regs + ECEINT);
+
+	/* Enable capture */
+	ecctl2 = readw(state->regs + ECCTL2);
+	ecctl2 |= ECCTL2_TSCTR_FREERUN | ECCTL2_REARM;
+	writew(ecctl2, state->regs + ECCTL2);
+	set_bit(ECAP_ENABLED, &state->flags);
+
+	ret = iio_triggered_buffer_postenable(idev);
+
+	return ret;
+}
+
+static const struct iio_buffer_setup_ops ecap_buffer_setup_ops = {
+	.postenable = &ecap_buffer_postenable,
+	.predisable = &ecap_buffer_predisable,
+};
+
+static void ecap_init_hw(struct iio_dev *idev)
+{
+	struct ecap_state *state = iio_priv(idev);
+
+	clear_bit(ECAP_ENABLED, &state->flags);
+	set_bit(ECAP_POLARITY_HIGH, &state->flags);
+
+	writew(ECCTL1_RUN_FREE | ECCTL1_CAPLDEN |
+	       ECCTL1_CAP2POL | ECCTL1_CTRRST1,
+	       state->regs + ECCTL1);
+
+	writew(ECCTL2_SYNCO_SEL_DIS | ECCTL2_STOP_WRAP_2,
+	       state->regs + ECCTL2);
+}
+
+static const struct of_device_id ecap_of_ids[] = {
+	{ .compatible	= "ti,am33xx-ecap" },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ecap_of_ids);
+
+static int ecap_probe(struct platform_device *pdev)
+{
+	int irq, ret;
+	struct iio_dev *idev;
+	struct ecap_state *state;
+	struct resource *r;
+	struct clk *clk;
+	struct iio_trigger *trig;
+	u16 status;
+
+	idev = devm_iio_device_alloc(&pdev->dev, sizeof(struct ecap_state));
+	if (!idev)
+		return -ENOMEM;
+
+	state = iio_priv(idev);
+
+	clk = devm_clk_get(&pdev->dev, "fck");
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "failed to get clock\n");
+		return PTR_ERR(clk);
+	}
+
+	state->clk_rate = clk_get_rate(clk);
+	if (!state->clk_rate) {
+		dev_err(&pdev->dev, "failed to get clock rate\n");
+		return -EINVAL;
+	}
+
+	platform_set_drvdata(pdev, idev);
+
+	idev->dev.parent = &pdev->dev;
+	idev->name = dev_name(&pdev->dev);
+	idev->modes = INDIO_DIRECT_MODE;
+	idev->info = &ecap_info;
+	idev->channels = ecap_channels;
+	/* One h/w capture and one s/w timestamp channel per instance */
+	idev->num_channels = 2;
+
+	trig = devm_iio_trigger_alloc(&pdev->dev, "%s-dev%d",
+				      idev->name, idev->id);
+	if (!trig)
+		return -ENOMEM;
+	trig->dev.parent = idev->dev.parent;
+	iio_trigger_set_drvdata(trig, idev);
+	trig->ops = &iio_interrupt_trigger_ops;
+
+	ret = iio_trigger_register(trig);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register trigger\n");
+		return ret;
+	}
+
+	ret = iio_triggered_buffer_setup(idev, NULL,
+					 &ecap_trigger_handler,
+					 &ecap_buffer_setup_ops);
+	if (ret)
+		return ret;
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no irq is specified\n");
+		return irq;
+	}
+	ret = devm_request_irq(&pdev->dev, irq,
+				&ecap_interrupt_handler,
+				0, dev_name(&pdev->dev), idev);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to request irq\n");
+		goto uninit_buffer;
+	}
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	state->regs = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(state->regs)) {
+		dev_err(&pdev->dev, "unable to remap registers\n");
+		ret = PTR_ERR(state->regs);
+		goto uninit_buffer;
+	};
+
+	ret = iio_device_register(idev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to register device\n");
+		goto uninit_buffer;
+	}
+
+	state->buf = devm_kzalloc(&idev->dev, idev->scan_bytes, GFP_KERNEL);
+	if (!state->buf) {
+		ret = -ENOMEM;
+		goto uninit_buffer;
+	}
+
+	pm_runtime_enable(&pdev->dev);
+	pm_runtime_get_sync(&pdev->dev);
+
+	status = pwmss_submodule_state_change(pdev->dev.parent,
+			PWMSS_ECAPCLK_EN);
+	if (!(status & PWMSS_ECAPCLK_EN_ACK)) {
+		dev_err(&pdev->dev, "failed to enable PWMSS config space clock\n");
+		ret = -EINVAL;
+		goto pwmss_clk_failure;
+	}
+
+	ecap_init_hw(idev);
+
+	pm_runtime_put_sync(&pdev->dev);
+
+	return 0;
+
+pwmss_clk_failure:
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	iio_device_unregister(idev);
+
+uninit_buffer:
+	iio_triggered_buffer_cleanup(idev);
+
+	return ret;
+}
+
+static int ecap_remove(struct platform_device *pdev)
+{
+	struct iio_dev *idev = platform_get_drvdata(pdev);
+
+	pm_runtime_get_sync(&pdev->dev);
+
+	pwmss_submodule_state_change(pdev->dev.parent, PWMSS_ECAPCLK_STOP_REQ);
+
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	iio_device_unregister(idev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int ecap_suspend(struct device *dev)
+{
+	struct ecap_state *state = dev_to_ecap_state(dev);
+
+	pm_runtime_get_sync(dev);
+	state->ctx.cap1 = readl(state->regs + CAP1);
+	state->ctx.cap2 = readl(state->regs + CAP2);
+	state->ctx.eceint = readw(state->regs + ECEINT);
+	state->ctx.ecctl1 = readw(state->regs + ECCTL1);
+	state->ctx.ecctl2 = readw(state->regs + ECCTL2);
+	pm_runtime_put_sync(dev);
+
+	/* If capture was active, disable ECAP */
+	if (test_bit(ECAP_ENABLED, &state->flags))
+		pm_runtime_put_sync(dev);
+
+	return 0;
+}
+
+static int ecap_resume(struct device *dev)
+{
+	struct ecap_state *state = dev_to_ecap_state(dev);
+
+	/* If capture was active, enable ECAP */
+	if (test_bit(ECAP_ENABLED, &state->flags))
+		pm_runtime_get_sync(dev);
+
+	pm_runtime_get_sync(dev);
+	writel(state->ctx.cap1, state->regs + CAP1);
+	writel(state->ctx.cap2, state->regs + CAP2);
+	writew(state->ctx.eceint, state->regs + ECEINT);
+	writew(state->ctx.ecctl1, state->regs + ECCTL1);
+	writew(state->ctx.ecctl2, state->regs + ECCTL2);
+	pm_runtime_put_sync(dev);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(ecap_pm_ops, ecap_suspend, ecap_resume);
+
+static struct platform_driver ecap_iio_driver = {
+	.driver = {
+		.name		= "ecap",
+		.owner		= THIS_MODULE,
+		.of_match_table = of_match_ptr(ecap_of_ids),
+		.pm		= &ecap_pm_ops,
+	},
+	.probe = ecap_probe,
+	.remove = ecap_remove,
+};
+
+module_platform_driver(ecap_iio_driver);
+
+MODULE_DESCRIPTION("ECAP IIO pulse capture driver");
+MODULE_AUTHOR("Matt Porter <mporter@linaro.org>");
+MODULE_LICENSE("GPL");